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I Firing a pistol in an environment with no external forces

  1. Sep 28, 2016 #1
    If one fires a pistol while holding it in one's hand, the pistol will exert a backwards force above the grip of the hand, causing the gun to both move backwards as well as exerting a torque, as the hand is essentially behaving as a fulcrum. If a pistol is fired in a gravity-free environment with no air resistance, and the pistol fires, and the backwards force occurs above the gun's centre of mass, will a torque be exerted and will the gun thus be made to rotate as well as move backwards?

    This question is puzzling because nothing acts as a fulcrum aside from perhaps it's centre of mass(?)
  2. jcsd
  3. Sep 28, 2016 #2


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    A fulcrum is not required for rotation. A torque contributes to angular momentum regardless.

    How about analyzing the problem with a free body diagram. One drawing to represent the pistol, the impulse from firing and the impulse from the hand. A second drawing to represent the pistol, the impulse from firing and no impulse from the hand.
  4. Sep 28, 2016 #3


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    Science Advisor

    You are aware that spacecraft use reaction engines to change orientation for decades now?
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